Morgan describes how, over time, planters came to use enslaved africans instead of indentured servants as laborers. why did virginia planters originally prefer indentured servants to slaves?

Because of the high mortality rates, owning a slave for a lifetime was not as convenient as indentured servants.

Explanation:

American Slavery, American Freedom is a 1975 book by historian Edmund Morgan. Using archival records, Morgan studies the contradiction between the political positions of Virginia in defense of freedom, and its status as the largest slave state in the United States.

When describing the transition of Virginia towards a slaveholding society, Morgan points out how despite the seeming convenience of slavery, plantation owners originally prefer indentured servants: "Because of the high mortality  among immigrants to Virginia, there could be no great advantage in  owning a man for a lifetime rather than a period of years, especially  since a slave cost ronghly twice as much as an indentured servant. If the chances of a man's dying during his five years in Virginia  were better than fifty-fifty -and it seems apparent that they were- and if English servants could be made to work as hard as  slaves, English servants for a five-year term were the better buy." (1975, pp. 297-298).